Gestational Diabetes Tied to Weight Gain Between Pregnancies

Action Points

Explain that a retrospective study found that women who gained BMI units between pregnancies had a greater risk of developing gestational diabetes in the second pregnancy, even if they had been free of the condition in the first.

Note that gestational diabetes in the first pregnancy was still the most common risk factor for the condition in the second pregnancy.

The amount of weight women gain after a first pregnancy is associated with their chances of developing gestational diabetes during the next one, researchers found.

Compared with women whose body mass index did not increase or decrease by more than 1 BMI unit, those who gained more than 1 BMI unit between pregnancies had their odds of gestational diabetes increase in a dose-response fashion (P<0.001 for the trend), according to Samantha Ehrlich, MPH, of Kaiser Permanente Division of Research in Oakland, Calif., and colleagues.

Conversely, women who lost weight had lower odds of gestational diabetes in a subsequent pregnancy, although only for those who started out overweight or obese, the researchers reported in the June issue of Obstetrics & Gynecology.

"Taken together, these results support the avoidance of gestational weight retention and postpartum weight gain to decrease the risk of gestational diabetes in a second pregnancy as well as the promotion of postpartum weight loss in overweight or obese women, particularly those with a history of gestational diabetes," they wrote.

Ehrlich and her colleagues performed a retrospective analysis of 22,351 women, ages 15 to 45, who delivered two live-born singletons at Kaiser Permanente Northern California from 1996 through 2006.

All underwent screening for gestational diabetes with the 50-gram, one-hour glucose challenge test. Those with plasma glucose values of 140 mg/dL or higher went to the 100-gram, three-hour oral glucose tolerance test for diagnosis.

Gestational diabetes was defined as two or more plasma glucose values meeting or exceeding the following thresholds:

Fasting: 95 mg/d

One-hour:180 mg/dL

Two-hour: 155 mg/dL

Three-hour: 140 mg/dL

Overall, 4.6% of the women had gestational diabetes in a first pregnancy, 5.2% had it in a second pregnancy, and 1.8% had it in both.

The age-adjusted risk of having gestational diabetes in the second pregnancy was 38.19% for women who had the condition in the first pregnancy, but only 3.52% for those whose first pregnancy was unaffected.

In the overall cohort, 10% of women lost BMI units between pregnancies and 53% gained BMI units. The authors noted that 1 BMI unit corresponded to 5.9 pounds for an average-height woman in the study (5 feet 4 inches).

Compared with women who maintained their BMI within 1 unit, those who gained at least 1 unit between pregnancies had an increased likelihood of developing gestational diabetes in the second pregnancy after adjusting for age, race and ethnicity, place of birth, gestational diabetes and BMI in the first pregnancy, gestational age at the weight measurements, and time interval between pregnancies:

1 to 1.9 units: OR 1.71 (95% CI 1.42 to 2.07)

2 to 2.9 units: OR 2.46 (95% CI 2.00 to 3.02)

3 or more units: OR 3.40 (95% CI 2.81 to 4.12)

The pattern held true for women regardless of whether they were overweight or obese during the first pregnancy.

The loss of BMI units between pregnancies was associated with a lower risk of gestational diabetes in the second pregnancy only for women who were overweight or obese for the first pregnancy:

1 to 2 units: OR 0.62 (95% CI 0.39 to 0.98)

More than 2 units: OR 0.26 (95% CI 0.14 to 0.47)

The researchers noted that the second half of pregnancy is characterized by an insulin-resistant state, although most women are able to increase insulin secretion to compensate.

"However, those women requiring the hypersecretion of insulin to compensate for pregnancy-induced insulin resistance may experience beta-cell exhaustion and gestational diabetes, yet there is some evidence that weight gain may also result in insulin resistance in the nonpregnant state," they wrote.

Thus, they speculated, weight gain in between pregnancies "may contribute to added beta-cell exhaustion and result in an inadequate secretion of insulin for the level of insulin resistance induced by a second pregnancy."

The authors noted some limitations of the study, including the use of body weight measurements during the first pregnancy to estimate BMI and the lack of information of some potential confounders, including physical activity, diet, and breastfeeding.

The study was conducted at the Kaiser Permanente Division of Research and supported by a grant from the National Institute of Diabetes and Digestive and Kidney Diseases and a Community Benefit grant from Kaiser Permanente Northern California.

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